There is a problem on Windows 8 with Firefox 19 and AMD Radeon HD 6XXX/7XXX graphic display cards.
This issue is currently being investigated in bug 830531 (please do not comment in bug reports).
*Bug 830531 - [Win8] crash in XPC_WN_Helper_NewResolve mainly with AMD Radeon HD 6290/6310/6320/7290/7310/7340
If you have one of those display cards then best is to stay with or downgrade to Firefox 18.0.2 for now or try the Firefox 20 beta version that doesn't seem to be affected.
*https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/18.0.2/win32/en-US/
*http://www.mozilla.org/en-US/firefox/beta/